The present invention relates to the field of improvements in safety and work scaffold catwalks, decks and platforms for use in utility construction projects, and more particularly providing temporary access and fall protection for safe access to un-backfilled sewer manholes, by use of a temporary installable and removable safety and work platform installed to the outside of the pre-fabricated manhole casing or utility openings during a utility construction project.
In the construction and installation of underground utilities, particularly water, sewer, and storm sewer utilities, there has been no safe way for construction workers to safely work on a manhole before or during installation of the manhole casing. During the construction process, a contractor must dig a hole for the construction casing and sewer or other utility line, varying in depth from four feet to thirty feet. Then, trench shoring may be provided to shore the construction excavation. Three to five concrete sections of manhole casing are first set in this excavation to provide the manhole access to the utility hole. The distance from top of the manhole casing to the floor of the excavation, therefore, can be considerable, creating a safety and work problem.
The manhole casing used in such utility construction is comprised of concrete sections having one of two shapes, a cone or conical shape for the surface access section and a vertical cylindrical shape for the remaining sections to the manhole construction. The conical section may be symmetrical or asymmetrical, and is typically asymmetrical in such utility construction in the industry.
A project surveyor will supply the contractor with a survey grade and alignment hubs in order for the first manhole casing section to be set on the utility line. When the first section is set “on grade”, and successfully surveyed and aligned, the contractor will then vertically stack the remaining sections of the manhole casing. The last or uppermost section of the manhole casing is generally an asymmetric conical section. A four-foot section of manhole casing is generally used as the industry standard for each section.
Where the conical section is asymmetrical, the conical section has a straight or vertical portion and an angled portion. The present invention provides adjustable braces to support a scaffolding deck or platform engaging the side of the manhole casing, to provide stability and support. Where there is an asymmetrical conical section, these braces must be of adjustable angles and lengths so that each may completely engage, in varying lengths, the respective, variable portions of the sidewalls of the asymmetrical conical section. It is an objective of the present invention to provide a scaffolding platform or deck supported with adjustable braces to securely support the platform against the sidewalls of any shape of manhole casing.
A pipe laser instrument is placed into the bottom section of the manhole in order to facilitate in assuring that the pipe coming out of the manhole is on grade. A transit survey instrument is used in cooperation with the laser instrument to ensure this alignment. The transit must be clamped by an equipment worker to the outer rim of the topmost conical section of the manhole casing, and a plumb bob is attached to the transit and lowered down through the manhole casing to a pre-determined point on the laser to establish “true line” and grade, thereby facilitating proper alignment.
Installation and operation of the transit and laser instruments are critical for establishing correct grade for the manhole casing and pipe. Currently, apart from the present invention, there is no way for an operator or worker to safely install a line level and survey instruments or to check and re-check the alignment of the manhole casing and pipe from the top of the manhole casing. Once the last manhole casing section is set, the operator has no safe way to install the drop transit from the edge of the top, conical section of the manhole casing. At this point in the construction project, the manhole casing is generally several feet above the base level of the excavation. One of the objects of the present invention is to solve a safety problem for the worker at this juncture of the process, allowing the operator to stand over the manhole casing to install the drop transit without the risk of falling or losing the equipment, another object of the present invention.
Pursuant to fall protection rules set forth by the U.S. Occupational Safety and Health Administration (“OSHA”) regulations, any situation where the operator or other worker is above six feet from the floor of the working space, he or she has to have adequate fall protection. Prior to the present invention, such workers have had no adequate means of standing on top of a manhole casing in order to install a drop transit on the side of the manhole casing to accomplish this alignment process or perform other activities, in view of the open excavation and safety issue and concurrently comply with the OSHA regulations. Another object of the present invention is to provide fall protection consistent with OSHA regulations for operations in the construction and installation of underground utilities with manhole casings.
The present invention, therefore, eliminates fall protection non-compliance in violation of OSHA regulations if installed on the manhole casing as provided by the device and method of the present invention.
A safety barrier means such as a handrail is installed with a work access opening on the perimeter of the scaffold catwalk to this embodiment of the present invention. A further object of the present invention is to accommodate access and egress to an un-backfilled manhole by use of the scaffold catwalk to the present invention with a safety barrier means such as handrails, thereby providing access to a safety barrier around the scaffold catwalk, further eliminating the danger of falls.
The device of the present invention slides over the top of the conical section of the manhole casing before the conical section is set on top of the vertical sections, thereby immediately providing fixed, safe access to the manhole casing, allowing workers to walk on the scaffold catwalk out to the top of the manhole casing and clamp the alignment grade survey instruments necessary to provide proper grade. The present invention gives access throughout the operation and installation of the utility line, such as a sewer line, and for removal of the alignment and grade instruments while at the same time providing adequate fall protection pursuant to law. The present invention gives safe and quick access to manhole casings during construction and installation of the manhole, another object of the invention.
As noted, a primary object of the present invention is to provide fall protection and access to the manhole casing for safe use by operators or other workers. Another object of the invention is to provide this fall protection in an efficient time frame. Prior inventions have no way of providing access to un-backfilled sewer manhole casings to set up the laser alignment transit and at the same time provide safe and OSHA-compliant access adequate for fall protection. Related art provides information regarding work platforms which may be installed on top of casing or other conduits, such as U.S. Pat. No. 5,295,557 to Taylor and U.S. Pat. No. 6,830,127 B2 to Johnson. Both Taylor and Johnson describe work platforms attached to and covering the top of manhole casings or conduits, with platforms adapted to engage and mount the top portion of a manhole during construction. Neither of these two references teach the features of the proposed device of the present invention, engaging the side of the manhole casing preferably below the top edge or providing for adjustable braces to support a scaffolding deck or platform against the sidewalls of said casing. Neither of the patents to Johnson or Taylor disclose a central opening for receiving the conical portion of the manhole. Nor can the other cited references be modified to receive such a manhole conical section. Therefore, these references cited as examples of prior related art fail to show, describe, or suggest the present invention. The present invention, as disclosed and claimed hereby provides distinct and useful advantages not previously known in this field of utility, construction, safety and work platforms.
References to related art provided further information teaching scaffolding devices for smokestacks and silos extending through a central opening, such as U.S. Pat. No. 20,653 to Lamb, and U.S. Pat. No. 2,623,643 to Seamans. Lamb and Seamans disclose scaffolding having braces extending beneath said scaffolding for supporting sidewalls of a silo or smokestack. However, neither Lamb nor Seamans disclose a concave platform in a single unit that circumferentially engages a conical casing. While Lamb and Seamans disclose braces extending beneath scaffolding for supporting sidewalls of a silo or smokestack, these devices are not adapted for use against an asymmetrical, conical or sloping sidewall and are not adjustable to perform such function. The braces of the present invention accommodate both the angled and vertical sidewalls of a manhole casing. The angular adjustment holes of the present invention are not an obvious modification of Seamans or Lamb because silos, smokestacks, and other disclosures of the prior related art do not have asymmetrical, conical walls in which such patented inventions have the adjustable braces as elements. While providing for some means of bracing, none of the related art patents provide the features of the adjustable braces found in the present invention. Therefore, the references cited as example of prior related art taken alone or in combination fail to show, describe, or suggest the present invention.
Still further objects of the present invention will become apparent from a consideration of the ensuing descriptions and drawings.